1. Field of the Invention
The present invention relates to an aqueous and hydrocarbon soluble diverting material or fluid-loss additive and a method for use of the material in the treatment of wells in subterranean formations.
2. Description of the Prior Art
In the treatment of fluid-containing subterranean formations penetrated by a well bore with various treatment fluids, there often is a need to incorporate a material in the treatment fluid which temporarily decreases the permeability of the formation to the treatment fluid. Otherwise, the treatment fluid can pass through existing channels, fissures, and the like in the formation without effecting the desired treatment. For example, when treating a heterogenous permeable formation with an acidizing fluid, it is important to contact the less permeable zones of the formation with acid if desired formation fluid flow is to be improved. Many additives generally known as diverting materials have been developed for this use. Also, when a formation is to be fractured utilizing a fracturing fluid, more efficient treatments can be achieved if the fracturing fluid is not lost to the formation. In these instances, fluid-loss additives are desirable. There also are other treatments where fluid loss control is desirable.
Numerous materials have been utilized as fluid loss additives and as diverting materials. Examples of such materials are disclosed in U.S. Pat. Nos. 3,374,835; 3,480,084; 3,724,549; 3,797,575; 3,827,498; 4,026,361, and the like. However, various problems exist in the use of the different materials. It is desirable that the material be suitable for use as either a fluid-loss additive or a diverting material, be stable in acidic solutions, and be easily removed from the formation subsequent to the treatment. Also, it is desirable that the material be able to pass through a gravel or sand pack so as to permit effective treatment of the formation located behind the pack.